Such water conditioning apparatus is well known. For example, some forms of domestic water softeners employ a tank containing resin beads having a coating of sodium ions. Hard water from a supply such as the water main is passed through the tank, and the sodium ions on the beads are exchanged with calcium and magnesium ions in the water so as to soften the water. Eventually, the resin beads become exhausted of sodium ions, and it is then necessary to recharging, or regenerate, the apparatus. In a known recharging process, there are five phases: (1) water is passed to a tank containing common salt which dissolves to form brine; (2) the brine is passed into the tank of resin beads where it filters through the beads to recharge them by replacing the calcium and magnesium ions with sodium ions; (3) water is passed through the tank of resin beads to wash away any remaining brine; (4) water is passed through the tank of resin beads in the opposite direction to remove any dirt or sediments; and (5) water is forced through the tank of resin beads in the normal direction to pack the resin beads ready to return to service. In order to avoid interrupting the supply of water to the house, during the last four of these phases, the water softener is bypassed so that water can be supplied to the house directly from the water main. Because the supplied water is not then softened, it is desirable that the recharging process takes place during periods of low, or no, water usage. To deal with this, it is known to control the recharging process of the softener by a timer, and the regeneration sequence is initiated at regular intervals, for example in the early morning when water usage might be assumed to be at its lowest.
One problem with this known form of control is that the time set for initiation of the recharging cycle may not necessarily always be a time when water usage is at its lowest. Another problem is that, in the event of power failure, many less expensive designs of timer will require resetting in order to avoid the recharging cycles occurring at the wrong times, possibly unbeknown to the consumer.
Similar issues arise in relation to other water conditioning apparatus, such as water filters. Such filters may need to be periodically recharged by backwashing to remove deposits. While the recharging operation is being carried out, then either the supply of water to the consumer must be cut off, or the consumer must be supplied with unfiltered water.
A first aspect of the present invention is concerned more particularly with a method of controlling recharging of a water conditioning apparatus, comprising the steps of: detecting water usage by the apparatus; storing for each time slot of a cyclically repeating series of such time slots information about the usage in that time slot; and determining, at least in part, a time for recharging the apparatus in dependence upon the stored information. Such a method is hinted at in patent document GB-A-2,177,232, although it is not apparent from that document how, during normal operation, recharging can actually take place once a determination to recharge has been made.
In the method of GB-A-2,177,232, the duration of each time slot is one hour, and the time slots repeat every four weeks. If there has been no water usage in a particular time slot, then that fact is stored. It appears that recharging is supposed to take place once required and at a time when the stored information for the particular time slot indicates zero usage. To deal with the case where there is never zero usage, it appears that the time slot for which there has been minimum usage is also stored, and that recharging can supposedly also take place once required and when the stored minimum usage time slot occurs.